INTRODUCTORY REMARKS(A brief description of the participating institutions

in the Seminar and scientific activities)

M. FONT-ALTABA

Institut d'Estudis Catalans.

The first Seminar on the Structure and Physical Properties of Crystalsheld in Barcelona (28 May to 1 June 1990) is a result of the agreement es-tablished between the Institut d'Estudis Catalans (IEC) and the Instituteof Crystallography (Moscow) of the USSR Academy of Sciences (ICM),signed in Moscow in July 1989.

This specific collaboration agreement established the exchange of in-formation and research work in the field of the structural analysis of crys-tals and the physical, biological and technical properties of crystalline ma-terials; it also provided for the interchange of scientific staff working incrystallography; and the commitment to organize an annual seminar, oneyear in Catalonia and the following in the USSR, dealing strictly with pro-blems of methods and results in the structural research carried out as partof this agreement, to be held at a high level of specialization and restrictedto ten persons from each party.

The Seminar was organized by the Institut d'Estudis Catalans andInstitute of Crystallography of Moscow with the help of different Centersof Barcelona which gave access to their laboratories and collaborated withsome research papers. The addresses of all these Institutions are as fo-llows:

Institut d'Estudis Catalans,Carme 47, 08001 Barcelona ; tel. (34-3) 318 55 16.

Institute of Crystallography, USSR Academy of Sciences,Leninsky Prosp. 59, Moscow 117333; tel (7-095) 135 64 00.

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162 M. FONT-ALTABA

Universitat de Barcelona,a) Departament de Cristal-lografia, Mineralogia i Diposits Minerals,

Marti i Franques s/n, 08028 Barcelona; (34-3) 402 13 43.

b) Facultat de Fisica, Departament de Fisica Fundamental,

Diagonal 647, 08028 Barcelona; tel. (34-3) 402 11 57.

Universitat Politecnica de Catalunya,

a) Departament d'Enginyeria Quimica, ETSEIB, and

Grup de Macromolecules, CSIC,

Diagonal 647, 08028 Barcelona; tel. (34-3) 401 66 88.

Consejo Superior de Investigaciones Cientificas,

a) Institut de Ciencia de Materials de Barcelona,

Campus Universitari I AB, Universitat Autonoma de Barcelona,

08193 Cerdanyola (Bellaterra); tel. (34-3) 580 18 53.

As this was the first institutional contact between most of the scien-

tists of the centers concerned, some of the lectures were dedicated to ex-

plaining the composition, equipment and type of work of the Institutions.

Professors Simonov, Solans and Subirana gave short lectures on the pro-

blems they have to obtain good research results with a normally limited

budget which, in general, is a problem faced by all the research centers in

the world. Effort and devotion on the part of scientists is the way to over-

come the deficiencies of public support, and to obtain good results and

new conclusions in the complicated problems of Science.

Professor B. K. Vainshtein, director of the Institute of Crystallogra-

phy of Moscow and academician of the USSR Academy of Sciences, and

Professor B. P. Sobolev, gave a lecture on their specific topics, proteins

and the non-stoichiometry of fluorites.

The lectures and research papers offered at the Seminar were divided

in three groups in accordance with their field: structure of crystals, met-

hods and applications; non-stoichiometry and phases in fluorites and the

crystal properties of superionic conductors; and macromolecules.

The first group (structure of crystals, methods and applications) star-

ted with the lecture by Professor V. I. Simonov, Assistant Director of the

Institute of Crystallography of Moscow, on "Atomic structure and physi-

cal properties of crystals", in this he explained their advances in the tech-

niques of accurate crystal structure analysis make it possible to establish

regular correlations between the atomic structure and physical properties

of crystalline materials; modern diffraction methods ensure not only a

high accuracy of the determination of atomic coordinates but also provide

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INTRODUCTORY RE.3IARtiS 163

reliable data on atomic thermal motion, with allowance for both anharmo-nic and deviations from the harmonic law; structural analysis yields ato-mic mechanisms of phase transitions in crystals, as well as qualitative cha-racteristics of isomorphous replacements in samples and the degree ofstructure perfection of a particular single crystal. During the lecture someresults of structural studies of high-temperature superconductors, crystalswith high ionic conductivity, ferroelectrics and some other crystalline ma-terials were presented. This was a highly interesting lecture which was fo-llowed with great attention by those present, who asked the lecturer spe-cial questions at the end.

The following speakers were Professor X. Solans, Director of the De-partment of Crystallography, Mineralogy and Mineral Deposits, togetherwith Professor M. Font-Altaba, who explained the situation of X-ray dif-fraction in our University in a lecture entitled "X-ray Diffraction andCrystal Structure at the University of Barcelona". The lecture includedsome problems arising in research and the complementary techniques usedin laboratories, such as goniometry, optical crystallography and electronmicroscopy. It listed the journals in which papers have been published andthe average number of publications per year.

Four research papers were presented orally: structure investigation oftwinned crystals, integration of Patterson function in direct methods, theatomic structure of sillenites and retamine bromide.

The second group (non -stoichiometry and phases in fluorites andcrystal properties of superionic conductors) began with the lecture ofProfessor B. P. Sobolev on "Non-stoichiometry in inorganic fluorides andphases with fluorite structure" in which he offered the results of theprogram of investigations carried out of over 200 phase diagrams of theMF,,,-RF„ type systems, comprising fluorides of 27 metals, such as Na, K,Sc, Y, La and lanthanides, Zr, Hf, Th, U. Numerous non-stoichiometricphases (heterovalent solid solutions) with a specific, partially disorderedstructure, are formed in them. These phases crystallize mostly in twostructural types: Cal', (49%)) and LaF3 (25`%), retaining their single-crystalline form upon cooling. Fluoride non-stoichiometric phases,formed in MF,-RF, and MF-RF3 systems, are of special interest as theyarc a new family of inorganic fluoride materials with controlled defectstructure and physical characteristics variable over a wide range. Themain, at present and most promising directions for the practical applica-tion of fluorite grossly non-stoichiometric phases for technologicalpurposes were considered.

Four research papers on X-ray and neutron diffraction studies, theassociation of point defects and the preparation of single crystals of multi-component fluoride materials and non-stoichiometry fluorite phases were

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164 A4. 1.0NT-AL7118A

expounded orally and discussed. Another three papers on molecular dyna-

mics simulation, structural features and intrinsic and impurity-induced

structure disorder of superionic conductors were also orally presented and

discussed.Professor B. K. Vainshtein presented a very interesting lecture in the

Institut d'Estudis Catalans on "Modern State and Perspectives of X-ray

Crystallography of Proteins". He considered the aims and principal possi-

bilities of the X-ray analysis of proteins; he gave a detailed description of

the structure of Lupinus Luteus leghemoglobin and the mechanism of oxy-

gen binding by this protein. Analysis of the structure of inorganic yeast

pyro-phosphatase (Saccharomyces cerevisiae) has been carried out. High

resolution structure study of five proteins in the family of specific micro-

bial and fungal ribonucleases has been made. A description was given of

the structure determination of complex protcins-catalases from various

sources: Penicillium vitale (m. w. 290 kDa), Micrococcus lysodeikticus (m.

w. 240 kDa), Thermus thermophilus (m. w. 210 kDa). The results obtained

allow the mechanism of enzymatic reactions catalysed by these proteins to

be explained. The lecture was attended by a large number of people who

asked the lecturer questions concerning different points of his talk.

The third group (macromolecules) started with a lecture by Professor

J. A. Subirana on "Research at the Macromolecular Chemistry Group in

Barcelona" in which he established that the Macro-molecular Chemistry

Group was created in the Department of Chemical Enginering of the Po-

lytechnic University of Catalonia about twenty years ago as a joint ventu-

re with the Consejo Superior de Investigaciones Cientificas, which has

supported the group at various levels during this time. In this period about

230 publications have been produced and 41 students have obtained a PhD

in the group. About 80%of them are now in academic positions. The

group concentrates on structural studies such as electron microscopy, in

frared spectroscopy, calorimetry and, more specifically, on X-ray diffrac-

tion. Several generations of collaborators have been access to pinhole and

low angle cameras only availabled. The most recent acquisition is a GX-21

rotating anode generator provided with a Enraft CAD4 automatic difrac-

tometer. The main lines of activity are: nuclear proteins, peptide models

and their complexes with DNA; to improve knowledge of basic proteins

it was decided to investigate several basic peptides in a systematic way,

since very few of them had been previously studied; oligonucleotides, ge-

nerally in fiber form, to understand nucleic acid structures; they have re-

cently started with the determination of protein structures by X-ray dif-

fraction; and several years ago studied the structure of polyamides which

might have an intermediate conformation between classical nylons, which

form sheet structures, and proteins, which often have helical structures.

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INTRODUCTORY REMARKS 165

He refered to the wholehearted dedication of his many colleagues, wit-hout whom the work carried out would no have been possible.

Five research papers were presented in this group, introducing theevaluation fo "free energy" for non-covalent interactions in protein stu-dies; crystallization and structure determination of an antibody; molecu-lar structure of a dipeptide; oligonucleotide-protein complexes; and mole-cular and crystalline structures by X-ray diffraction with stereochemicalrestriction.

The organizing commission hope that scientists found this Seminarinteresting, and hope to meet the same interest at the II Seminar to be heldin the USSR next year.

ABSTRACT

The Seminar was organized by the Institut d ' Estudis Catalans and the Instituteof Crystallography of Moscow . The Centres of Barcelona which gave access to theirlaboratories and collaborated with some research papers were : Department of Crysta-llography, Mineralogy and Mineral Deposits , and Department of Fundamental Phy-sics of the Barcelona University ; Department of Chemical Engineering and Group ofMacromolecular Structures of Polytechnic University of Catalonia ; Material SciencesInstitute of Consejo Superior de Investigaciones Cientificas (CSIC).

The lectures and research papers offered at the seminar were divided in threegroups in accordance with their field : structure of crystals , methods and applications;non-stoichiometry and phases in fluorites and the crystal properties of superionicconductors ; and macromolecules.

Professors B. K. Vainshtein and B . V. Sobolev gave a lecture on their specific to-pics, proteins and the non-stoichiometry of fluorites . Professors V. I. Simonov, X.Solans and J. A. Subirana gave a short lectures on the problems to obtain good resultsand new conclusions in their Institutes.

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